Ink-jet color printing system

An ink-jet color printing method for forming a color picture in the form of dot patterns with ink dots of a plurality of colors on a recording medium, comprising the following steps:

• (1) utilizing ink-jet color printing apparatus comprising:
• color image information input means for receiving color image information of picture elements in the form of digital signals;
• memory means for memorizing the said digital signals of the color image information;
• image processing means for masking said digital signals of the color image information;
• head assembly means closely adjacent said recording medium, including at least a group of ink-jet heads for ejecting yellow ink drops, a group of ink-jet heads for ejecting magenta ink drops and a group of ink-jet heads for ejecting cyan ink drops;
• two-dimension scanning means for scanning the surface of said recording medium by a continuous motion of said head assembly relative to said recording medium and an intermittent motion of said head assembly relative to said recording medium in the direction perpendicular to that of said continuous motion;
• detecting means for detecting positions of said head assembly relative to said recording medium in the direction of said continuous motion to generate first signals;
• a plurality of detecting means for detecting positions of said groups of ink-jet heads, respectively, in the direction of said intermittent motion to generate second signals;
• information read-out means for reading the color image information from said memory means corresponding to said second signals;
• and
• means for each group of ink-jet heads to convert color density signals of a single color of ink drops to be ejected by said ink-jet heads extracted from said color image information into analog signals and to feed said analog signals to said ink-jet heads corresponding to said first signals in order to drive them;
• (2) utilizing a masking technique comprising carrying out a non-linear masking procedure;
• (3) utilizing aqueous ink comprising yellow dye of the formula [I] hereinbelow supplied into the said yellow ink-jet head;
• (4) utilizing aqueous ink comprising magenta dye of the formulae [II-a], [II-b] or [II-c] hereinbelow supplied into the said magenta ink-jet head;
• and
• (5) utilizing aqueous ink comprising cyan dye of the formula [III] hereinbelow supplied into the said cyan ink-jet head;
• ##STR19## wherein R.sub.1 is amino or acylamino, R.sub.2 is phenyl, substituted phenyl, lower alkyl or substituted lower alkyl, R.sub.3 is lower alkyl or phenyl, X.sub.1 is halogen, lower alkyl, alkoxy, sulfo, carboxyl, amino, substituted amino, cyano, alkylsulfonyl, nitro, hydroxy, ureido or alkoxycarbonyl, j is 0, 1, 2 or 3, provided that when j is 2 or 3, X.sub.1 can be the same or different and the number of sulfo groups is 1-3;
• ##STR20## wherein R.sub.4 is cyano, alkylsulfonyl, arylsulfonyl, trifluoromethyl, trichloromethyl, or halogen, R.sub.5 is amino, acylamino, substituted ureido, alkoxy or acyloxy, R.sub.6 is hydrogen, lower alkyl, phenyl or acyl, and k is 0 or 1;
• ##STR21## wherein R.sub.7 is hydrogen, acyl, lower alkyl or phenyl, X.sub.2 is halogen, lower alkyl, alkoxy, sulfo, carboxyl, amino, substituted amino, cyano, alkylsulfonyl, nitro, hydroxy, ureido or alkoxycarbonyl, l is 0 or 1, m is 0, 1, 2 or 3, and when m is 2 or 3, X.sub.2 may be the same or different;
• ##STR22## wherein R.sub.8 is hydrogen, lower alkyl or phenyl, R.sub.9 is hydrogen, lower alkyl, phenyl, alkoxycarbonyl, carboxyl or cyano, X.sub.3 is lower alkyl, halogen, alkoxy, carboxyl, cyano, hydroxy or nitro, X.sub.4 is hydrogen or lower alkyl, n is 1, 2 or 3, p is 0, 1, 2, 3 or 4, provided that when p is more than 2, X.sub.3 may be the same or different. ##STR23## wherein q is 1 to 4, and the metal salts, ammonium salts and organic amine salts of the sulfone groups in formulae [I], [II-a], [II-b], [II-c] and [III].